CA2124088A1 - Bleaching of chemical pulp - Google Patents
Bleaching of chemical pulpInfo
- Publication number
- CA2124088A1 CA2124088A1 CA002124088A CA2124088A CA2124088A1 CA 2124088 A1 CA2124088 A1 CA 2124088A1 CA 002124088 A CA002124088 A CA 002124088A CA 2124088 A CA2124088 A CA 2124088A CA 2124088 A1 CA2124088 A1 CA 2124088A1
- Authority
- CA
- Canada
- Prior art keywords
- pulp
- bleaching
- complexing agent
- peroxide
- consistency
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/147—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications
- D21C9/153—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications with ozone
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/1057—Multistage, with compounds cited in more than one sub-group D21C9/10, D21C9/12, D21C9/16
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/147—Bleaching ; Apparatus therefor with oxygen or its allotropic modifications
-
- D—TEXTILES; PAPER
- D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
- D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
- D21C9/10—Bleaching ; Apparatus therefor
- D21C9/16—Bleaching ; Apparatus therefor with per compounds
- D21C9/163—Bleaching ; Apparatus therefor with per compounds with peroxides
Landscapes
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Wood Science & Technology (AREA)
- Paper (AREA)
- Detergent Compositions (AREA)
Abstract
A method of bleaching sulphate pulp without using chlorine-containing bleaching agents. The sulphate pulp is oxygen delignified and can possibly also be ozone delignified to a kappa number below 9.5. Thereafter a pretreatment with complexing agent is carried out for 1-60 minutes, at which the pulp consistency is 1-15 %, the temperature 70-110 ·C and pH 5-7. The pulp thus pretreated is washed and dewatered to a consistency of 18-40 %. Thereafter peroxide bleaching in alkaline environment takes place in the presence of silicate or an organic complexing agent of the type phosphonic or carboxylic acid.
Description
212~88 Bleachin~ of chemical pulp ~:
This invention relates to the bleaching of sulphate pulp without using bleaching agents containing chlorine. The technique o~ bleaching chemical pulps is now developing rapidly, bec~use the bleaching chemicals hereto~ore mainly -used, Cl2, C102, and hypochl~rite, are fearsd to give ri~e to products being a risk ~or ~be environment and health.
Until now, the discussions have been concentrated on the emissions o* chlori~at~d organic subs~ance to ~he recipient.
Tha ma;ority o~ the cou~tries in th~ world ha~e now establ~
ished limit ~alueR for these emis~ions 9' which normally are measured as AOX (Adsorbable organ:ic halogens). As a new trPnd, the customers require t~ an ever increasing degree paper with a low cont~nt of chlor:inated organic su~stance~
Conventio~al bl~ach~ng ~ith Cl2 dL~appear~ now more and -~
more, and Cl2 is replacsd primari:Ly by ClO2~ Bleaching with GlO2 c&uses substa~t~all~ lower AOX emissio~s to the recipient, but the amoun~ of chlorinated ~ubstance in t~e pulp is a~cted only insigni~icantly.
In recent years, the use o~ hydrop~roxide t the bleaching of chemical pulps h~s increased considerably. Hydr~peroxide can replace part o~ the chlorine chemicals.
In patent application SE 89 02058 O, a method is described at which the pulp is pretreated with complexing agent under neutral conditionsO B~ this process, coniferou~ sulphate pulp can ~e bleached with peroxide-containing bleaching agents to 70 7~% ISO a~ about 10~ pulp consistency. In ord~r to achieve fully bleached pulp qualities with higher ISO-brightness (above 83~ ISO~, th s p~ocess can be combined with final bleaching ~ith ClO2. As a result, t~is final bleaching then yiel~s emission of AOX from the bleach plant and chlorinated organic susbstance in the bleached pulp. ~;
W0~3/14262 PCT/SE93/00012 2124~
.~,.
Other known methods of reducing emissions of chlorinated organic substance to the recipient are to extend the delignification further in the closed part Or the mill, i . e . in the digester house and/or oxygen step. ;~
Extended diges~on with maintained pulp quality can be achieved by impregnating the chips with black liquor in the initial phase of the cooX, as described in Finni~h patent ~pplication 90 0663. This method renders it possible to digest pulp down to a kappa number of about 10 and obtain str~ngth prop~rtie s equal to or better than with pulp digested to convention~l level ~ kappa number 25-30.
Combined w~th oxygen de7igni~ication, kappa numbers as low as 5-6 can be obtained ~o~.further bleachingO
By combining con~rentional digesti~n ~ oxy~en delignificat-ion and ozon~ bleac~i~g in acid environment, kappa numbers lower than 10 can be obtained~
It has~ however, no~ been po~sible to produce fully bleach- ~`
ed pulp qualities without final bleaching with ClO2.
The present in~ention implies 9 that fully bleached pulp with a bright~ess above 83% I50 can be made without the use of chlorine-containing bleaching agents.
At the s.tart of the bleaching, the pulp shall have a kappa number below 9 . 5 . This cE~n be achieved by conventional or extended digestion followed by 02-delignification, altern-atively by conventional or extended digestion fQllowed by 2- and 03~-deligni~ication~ The bleaching i~ initiated by a pretreatrnent step with ~::omplexing agent followed by tr~atment with hydropero~ide~ in al~aline en~rironment in the presence o~ silicate ~r an organic complexing agent :~
of the type phosph~nic or carboxyllc acid.
W0~3/14262 PCT/SE93/00012 3 212~
The characterizing features of the in~ention are appar-ent ~rom the attached claims.
The pulp digested and delignified with oxyg~n and possibly ozone according to above shall ha~e a kappa number below 9.~. This can be achieved by known methods o~, digestion and delignific~tion. The pulp ~hall therea~ter be pretreated with complexing agent, for example EDTA or DTPA, at a pulp ~;
consistency of 1-15~ ~or 1-60 minutes, preferably S-30 minutes. The temperature shall be 70-100C, preferably 80-100C, and the pH-value 5-7.
The pulp thus pr~treated is washed and dewatered to a con-sistency o~ 18-40%, preferably 20-30%. The pH-v~lue is increased to alkaline level, and hydrDparoxide is added together with silicate, for example ~odium silicate, alt-erna~vel~ together ~ith an organic complexing agent of the ~yp~ phosphonic or carboxylic acid. The dwell time o~ the pulp in thi~ hydrop~roxide ~tep shall be ~/2 - S hours, ::
preferably 1-4 hours, and th~ tempexature 70-1 oo5c, pre~-erably 8~-100C. The silica~e charge shall be 2-30 kg/ton pulp, prefe~ably 5-15 kg/ton pulp, expre~sed as SiO~. -Al~ernatively, the charge of the organic complexing agent shall be 0.~-5 kg/ton pulp.
Fig~ 1 is a diagram, in which the brightness o~ the pulp is plo~ted as a function of the pulp consi~tency at the ~::
peroxide bleaching,partly at conventional peroxide bleach-i~g and par~ly at bleaching according to the inv ntion~
The starting pulp was oxygen-delignified coniferous wood sulphate pulp with kappa number 6.5 (10.5 a~ter digestion)~
Curve 1 show~.conventional peroxide bleaching, with a con-~umption of H20z of 2~ kg/ton pulp. Cur~e 2 and t respect- ~
ivel~, 3 ref~P to bleaching according to the invention 1~ th ~:
silicate addition and a consumption of H202 of 20 and, respectiYely, 30 kg/ton pulp.
21~408~
It appears from the diagram how the brightness, after bleaching according to the invention a~d, respe.~tively, after conventional bleaching~ depends on the pulp con-sistency. At about 12% pulp consistency, the brightness obtained i5 equal in both cases, but at increased pulp consistency in the peroxid0 step an increased brightness is obtained according to the invention~ ~hile convention-al peroxids bleachi~g results in a deteriorated bright , ness.
The ~ollowing ex~mples ha~e the object to additionally elucidate th~ in~ention and i~s adv~ntages.
Example 1 An oxygen-deligni~ied co~iferous wood sulpha~e pulp (Scandina~ian fir/pine) with kappa number 6.4 ~10.5 after digestio~ according to a~ove Finn~sh paten~ applic-ation 90 0663)~ brightne3s 43~ IS0, intrinsic ~i~cosity 605 dm3/kg, wa~ pr~treat~d with complexing agent and peroxide bleached according to the i~vention.
Pretreatment _ ,, , Pulp consistency % 5 Time min 15 Temperature ~C 90 EDTA ~g/ton 2 -:~
Final pH 6.1 ~x~l~ ~0, ....
Pulp consistency % 25 Time min 240 Temperature C 90 SiO2 kg/ton 10 :
H22 consumption kg/ton 13.5 32.0 Final pH_ 10.2 10.3 Brightness % IS0 79.6 84,2 Intrinsic viscosity dm3/kg 520 447 WO93/l4262 PCT/SE93/00012 212~88 Example 2 A coniferous w~od sulphate pulp with kappa number 13.3 (digested of Scandina~ian fir/pine according to ~innish patent application 90 0663), oxygen delignlfied to kappa ~:
number 8.3:and ozone bleached in acid environment to kap- :
pa number 3.2, brightness 61% IS0, intrinsic viscosity 582 dm3/Xg, was bleached according to the inventio~
Pretreatment a~ in Exampls 1 Peroxide bleachin,~, Pulp cons.istency % 2 Time min . 240 Temperature G 90 SiO2 kg/ton 10 H22 consumption kg/ton 7.3 14.2 3091 Final pH 8.9 9.5 10 Bri~htnesq % ISQ 85~3 88r~ 90 Intrinsic viscosity dm3/~g 536 ~98 420 ~-Example .
An oxygen deligni~isd co~ rous wood sulphate pulp (digested of Pinus taeda according to Finnish patent application 90 0663) with kappa numb~r 9.9, ozone bleach~
ed to kappa number 4.8, brightne~ S4.$~ IS0, intrins~
ic ~iscosity 607 dm3lkg was pretreated and bleached according to the invention.
Pretreatment as in Example 1 , ............................................................ ..
' Perox_de b~
~, Pulp consi~tency % 25 Time min 2~0 Temperature C 90 SiO2 kg/ton 10 ,~
H22 consumption kg/ton 7.9 14.6 29.6 Final pH 10.2 10.4 10.6 ~' WO~3/14262 PCT/SE~3/000l2 2~2 ~o~ ~ 6 Brightness % IS0 81.3 85.~ 87.8 Intrinsic viscosity dm3/kg 570 534 459.
E~ample ~
An oxygen delignified birch sulphate pulp with kappa number 9.0, brightness 59.4~ IS0 and intrinsic ~iscos-ity 996 dm3/kg was bleached according to the invention..
Pretroatment as in Example 1 ::
Peroxide b~ eg Pulp consi~i~enky ~ . 25 Time min ~0 Temperature ~C .90 SiO2 kg/ton 10 H22 conSumptiOn kg/ton 8.~ 17~5 35 Final pH ~0.~ 10.~ 10~5 Brightn~s~ % IS0 82.2 85.5 86~5 ;~
Intrinsic YiSCosit~ dm3/~g 903 975 &22 .;
," ..~
The in~elltion i5 not reætricted to the embodimen~s set -.
~orth abov~, but can b~ varied within the scope o~ the invention idoa. I :
This invention relates to the bleaching of sulphate pulp without using bleaching agents containing chlorine. The technique o~ bleaching chemical pulps is now developing rapidly, bec~use the bleaching chemicals hereto~ore mainly -used, Cl2, C102, and hypochl~rite, are fearsd to give ri~e to products being a risk ~or ~be environment and health.
Until now, the discussions have been concentrated on the emissions o* chlori~at~d organic subs~ance to ~he recipient.
Tha ma;ority o~ the cou~tries in th~ world ha~e now establ~
ished limit ~alueR for these emis~ions 9' which normally are measured as AOX (Adsorbable organ:ic halogens). As a new trPnd, the customers require t~ an ever increasing degree paper with a low cont~nt of chlor:inated organic su~stance~
Conventio~al bl~ach~ng ~ith Cl2 dL~appear~ now more and -~
more, and Cl2 is replacsd primari:Ly by ClO2~ Bleaching with GlO2 c&uses substa~t~all~ lower AOX emissio~s to the recipient, but the amoun~ of chlorinated ~ubstance in t~e pulp is a~cted only insigni~icantly.
In recent years, the use o~ hydrop~roxide t the bleaching of chemical pulps h~s increased considerably. Hydr~peroxide can replace part o~ the chlorine chemicals.
In patent application SE 89 02058 O, a method is described at which the pulp is pretreated with complexing agent under neutral conditionsO B~ this process, coniferou~ sulphate pulp can ~e bleached with peroxide-containing bleaching agents to 70 7~% ISO a~ about 10~ pulp consistency. In ord~r to achieve fully bleached pulp qualities with higher ISO-brightness (above 83~ ISO~, th s p~ocess can be combined with final bleaching ~ith ClO2. As a result, t~is final bleaching then yiel~s emission of AOX from the bleach plant and chlorinated organic susbstance in the bleached pulp. ~;
W0~3/14262 PCT/SE93/00012 2124~
.~,.
Other known methods of reducing emissions of chlorinated organic substance to the recipient are to extend the delignification further in the closed part Or the mill, i . e . in the digester house and/or oxygen step. ;~
Extended diges~on with maintained pulp quality can be achieved by impregnating the chips with black liquor in the initial phase of the cooX, as described in Finni~h patent ~pplication 90 0663. This method renders it possible to digest pulp down to a kappa number of about 10 and obtain str~ngth prop~rtie s equal to or better than with pulp digested to convention~l level ~ kappa number 25-30.
Combined w~th oxygen de7igni~ication, kappa numbers as low as 5-6 can be obtained ~o~.further bleachingO
By combining con~rentional digesti~n ~ oxy~en delignificat-ion and ozon~ bleac~i~g in acid environment, kappa numbers lower than 10 can be obtained~
It has~ however, no~ been po~sible to produce fully bleach- ~`
ed pulp qualities without final bleaching with ClO2.
The present in~ention implies 9 that fully bleached pulp with a bright~ess above 83% I50 can be made without the use of chlorine-containing bleaching agents.
At the s.tart of the bleaching, the pulp shall have a kappa number below 9 . 5 . This cE~n be achieved by conventional or extended digestion followed by 02-delignification, altern-atively by conventional or extended digestion fQllowed by 2- and 03~-deligni~ication~ The bleaching i~ initiated by a pretreatrnent step with ~::omplexing agent followed by tr~atment with hydropero~ide~ in al~aline en~rironment in the presence o~ silicate ~r an organic complexing agent :~
of the type phosph~nic or carboxyllc acid.
W0~3/14262 PCT/SE93/00012 3 212~
The characterizing features of the in~ention are appar-ent ~rom the attached claims.
The pulp digested and delignified with oxyg~n and possibly ozone according to above shall ha~e a kappa number below 9.~. This can be achieved by known methods o~, digestion and delignific~tion. The pulp ~hall therea~ter be pretreated with complexing agent, for example EDTA or DTPA, at a pulp ~;
consistency of 1-15~ ~or 1-60 minutes, preferably S-30 minutes. The temperature shall be 70-100C, preferably 80-100C, and the pH-value 5-7.
The pulp thus pr~treated is washed and dewatered to a con-sistency o~ 18-40%, preferably 20-30%. The pH-v~lue is increased to alkaline level, and hydrDparoxide is added together with silicate, for example ~odium silicate, alt-erna~vel~ together ~ith an organic complexing agent of the ~yp~ phosphonic or carboxylic acid. The dwell time o~ the pulp in thi~ hydrop~roxide ~tep shall be ~/2 - S hours, ::
preferably 1-4 hours, and th~ tempexature 70-1 oo5c, pre~-erably 8~-100C. The silica~e charge shall be 2-30 kg/ton pulp, prefe~ably 5-15 kg/ton pulp, expre~sed as SiO~. -Al~ernatively, the charge of the organic complexing agent shall be 0.~-5 kg/ton pulp.
Fig~ 1 is a diagram, in which the brightness o~ the pulp is plo~ted as a function of the pulp consi~tency at the ~::
peroxide bleaching,partly at conventional peroxide bleach-i~g and par~ly at bleaching according to the inv ntion~
The starting pulp was oxygen-delignified coniferous wood sulphate pulp with kappa number 6.5 (10.5 a~ter digestion)~
Curve 1 show~.conventional peroxide bleaching, with a con-~umption of H20z of 2~ kg/ton pulp. Cur~e 2 and t respect- ~
ivel~, 3 ref~P to bleaching according to the invention 1~ th ~:
silicate addition and a consumption of H202 of 20 and, respectiYely, 30 kg/ton pulp.
21~408~
It appears from the diagram how the brightness, after bleaching according to the invention a~d, respe.~tively, after conventional bleaching~ depends on the pulp con-sistency. At about 12% pulp consistency, the brightness obtained i5 equal in both cases, but at increased pulp consistency in the peroxid0 step an increased brightness is obtained according to the invention~ ~hile convention-al peroxids bleachi~g results in a deteriorated bright , ness.
The ~ollowing ex~mples ha~e the object to additionally elucidate th~ in~ention and i~s adv~ntages.
Example 1 An oxygen-deligni~ied co~iferous wood sulpha~e pulp (Scandina~ian fir/pine) with kappa number 6.4 ~10.5 after digestio~ according to a~ove Finn~sh paten~ applic-ation 90 0663)~ brightne3s 43~ IS0, intrinsic ~i~cosity 605 dm3/kg, wa~ pr~treat~d with complexing agent and peroxide bleached according to the i~vention.
Pretreatment _ ,, , Pulp consistency % 5 Time min 15 Temperature ~C 90 EDTA ~g/ton 2 -:~
Final pH 6.1 ~x~l~ ~0, ....
Pulp consistency % 25 Time min 240 Temperature C 90 SiO2 kg/ton 10 :
H22 consumption kg/ton 13.5 32.0 Final pH_ 10.2 10.3 Brightness % IS0 79.6 84,2 Intrinsic viscosity dm3/kg 520 447 WO93/l4262 PCT/SE93/00012 212~88 Example 2 A coniferous w~od sulphate pulp with kappa number 13.3 (digested of Scandina~ian fir/pine according to ~innish patent application 90 0663), oxygen delignlfied to kappa ~:
number 8.3:and ozone bleached in acid environment to kap- :
pa number 3.2, brightness 61% IS0, intrinsic viscosity 582 dm3/Xg, was bleached according to the inventio~
Pretreatment a~ in Exampls 1 Peroxide bleachin,~, Pulp cons.istency % 2 Time min . 240 Temperature G 90 SiO2 kg/ton 10 H22 consumption kg/ton 7.3 14.2 3091 Final pH 8.9 9.5 10 Bri~htnesq % ISQ 85~3 88r~ 90 Intrinsic viscosity dm3/~g 536 ~98 420 ~-Example .
An oxygen deligni~isd co~ rous wood sulphate pulp (digested of Pinus taeda according to Finnish patent application 90 0663) with kappa numb~r 9.9, ozone bleach~
ed to kappa number 4.8, brightne~ S4.$~ IS0, intrins~
ic ~iscosity 607 dm3lkg was pretreated and bleached according to the invention.
Pretreatment as in Example 1 , ............................................................ ..
' Perox_de b~
~, Pulp consi~tency % 25 Time min 2~0 Temperature C 90 SiO2 kg/ton 10 ,~
H22 consumption kg/ton 7.9 14.6 29.6 Final pH 10.2 10.4 10.6 ~' WO~3/14262 PCT/SE~3/000l2 2~2 ~o~ ~ 6 Brightness % IS0 81.3 85.~ 87.8 Intrinsic viscosity dm3/kg 570 534 459.
E~ample ~
An oxygen delignified birch sulphate pulp with kappa number 9.0, brightness 59.4~ IS0 and intrinsic ~iscos-ity 996 dm3/kg was bleached according to the invention..
Pretroatment as in Example 1 ::
Peroxide b~ eg Pulp consi~i~enky ~ . 25 Time min ~0 Temperature ~C .90 SiO2 kg/ton 10 H22 conSumptiOn kg/ton 8.~ 17~5 35 Final pH ~0.~ 10.~ 10~5 Brightn~s~ % IS0 82.2 85.5 86~5 ;~
Intrinsic YiSCosit~ dm3/~g 903 975 &22 .;
," ..~
The in~elltion i5 not reætricted to the embodimen~s set -.
~orth abov~, but can b~ varied within the scope o~ the invention idoa. I :
Claims (6)
1. A method of bleaching sulphate pulp without using chlorine-containing bleaching agents, comprising oxygen delignification and possibly ozone delignification of the pulp to a kappa number below 9.5 and subsequent peroxide bleaching, c h a r a c t e r i z e d i n that the pulp directly after the delignification is pretreated with complexing agent for 1-60 minutes, the pulp consistency being 1-15%, the temperature 70-110°C
and pH 5-7, and that the pulp thus pretreated is washed and dewatered to a consistency of 18-40% and thereafter peroxide bleached in alkaline environment in the pres-ence of silicate or an organic complexing agent of the type phosphonic or carboxylic acid.
and pH 5-7, and that the pulp thus pretreated is washed and dewatered to a consistency of 18-40% and thereafter peroxide bleached in alkaline environment in the pres-ence of silicate or an organic complexing agent of the type phosphonic or carboxylic acid.
2. A method as defined in claim 1, c h a r a c t e r -i z e d i n that the peroxide bleaching is carried out for 1/2-5 hours at the temperature 70-110°C.
3. A method as defined in claim 1 or 2, c h a r a c t-e r i z e d i n that as complexing agent at the pretreatment EDTA or DTPA is used.
4. A method as defined in any one of the preceding claims, c h a r a c t e r i z e d i n that at the peroxide bleaching silicate is added in an amount of 2-30 kg/ton pulp, expressed as SiO2.
5. A method as defined in any one of the claims 1-3, c h a r a c t e r i z e d i n that at the peroxide bleaching an organic complexing agent of the type phos-phonic acid or carboxylic acid is added in an amount of 0.5-5 kg/ton pulp.
6. A method as defined in any one of the preceding claims, c h a r a c t e r i z e d i n that the bleaching is carried out to a brightness exceeding 83% ISO.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| SE9200152-8 | 1992-01-21 | ||
| SE9200152A SE469842C (en) | 1992-01-21 | 1992-01-21 | Bleaching of chemical pulp with peroxide |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2124088A1 true CA2124088A1 (en) | 1993-07-22 |
Family
ID=20385065
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002124088A Abandoned CA2124088A1 (en) | 1992-01-21 | 1993-01-12 | Bleaching of chemical pulp |
Country Status (14)
| Country | Link |
|---|---|
| EP (1) | EP0621915B1 (en) |
| JP (1) | JPH07503042A (en) |
| AT (1) | ATE151826T1 (en) |
| AU (1) | AU653467B2 (en) |
| BR (1) | BR9305761A (en) |
| CA (1) | CA2124088A1 (en) |
| DE (1) | DE69309893T2 (en) |
| ES (1) | ES2102008T3 (en) |
| FI (1) | FI943431A0 (en) |
| NO (1) | NO942718L (en) |
| NZ (1) | NZ246713A (en) |
| SE (1) | SE469842C (en) |
| WO (1) | WO1993014262A1 (en) |
| ZA (1) | ZA93317B (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE1004674A3 (en) * | 1991-03-11 | 1993-01-12 | Interox Internat Sa | Method of laundering of chemical pulp and application of the method of laundering pulp kraft. |
| BE1006056A3 (en) * | 1992-07-06 | 1994-05-03 | Solvay Interox | Method of laundering of chemical pulp. |
| SE501253E8 (en) * | 1993-06-08 | 1994-12-19 | Chlorine-free bleaching of chemical pulp | |
| SE9301960L (en) * | 1993-06-08 | 1994-07-25 | Kvaerner Pulping Tech | Bleaching of chemical pulp with peroxide at overpressure |
| JPH09502229A (en) * | 1993-09-02 | 1997-03-04 | ユニオン キャンプ パテント ホールディング インコーポレイテッド | Improved bleaching method for lignocellulosic pulp |
| BE1007757A3 (en) * | 1993-11-10 | 1995-10-17 | Solvay Interox | Method of laundering of chemical pulp. |
| FR2719854B1 (en) * | 1994-05-11 | 1996-06-21 | Atochem Elf Sa | Process for the preparation of delignified and bleached chemical paper pulps. |
| SE514697C2 (en) * | 1994-08-31 | 2001-04-02 | Valmet Fibertech Ab | Elimination of metal ions in pulp bleaching |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB8620222D0 (en) * | 1986-08-20 | 1986-10-01 | Abitibi Price Inc | Peroxide bleaching |
| US4732650A (en) * | 1986-09-15 | 1988-03-22 | The Dow Chemical Company | Bleaching of cellulosic pulps using hydrogen peroxide |
| DE69004492T3 (en) * | 1989-06-06 | 2001-11-15 | Eka Nobel Ab | Process for bleaching pulps containing lignocellulose. |
| FI93866B (en) * | 1990-02-09 | 1995-02-28 | Sunds Defibrator Rauma Oy | Method for preparing sulphate pulp |
-
1992
- 1992-01-21 SE SE9200152A patent/SE469842C/en unknown
-
1993
- 1993-01-12 DE DE69309893T patent/DE69309893T2/en not_active Expired - Fee Related
- 1993-01-12 BR BR9305761A patent/BR9305761A/en not_active Application Discontinuation
- 1993-01-12 WO PCT/SE1993/000012 patent/WO1993014262A1/en active IP Right Grant
- 1993-01-12 AT AT93902618T patent/ATE151826T1/en not_active IP Right Cessation
- 1993-01-12 JP JP5512379A patent/JPH07503042A/en active Pending
- 1993-01-12 CA CA002124088A patent/CA2124088A1/en not_active Abandoned
- 1993-01-12 AU AU34125/93A patent/AU653467B2/en not_active Ceased
- 1993-01-12 EP EP93902618A patent/EP0621915B1/en not_active Expired - Lifetime
- 1993-01-12 ES ES93902618T patent/ES2102008T3/en not_active Expired - Lifetime
- 1993-01-12 NZ NZ246713A patent/NZ246713A/en unknown
- 1993-01-18 ZA ZA93317A patent/ZA93317B/en unknown
-
1994
- 1994-07-20 NO NO942718A patent/NO942718L/en unknown
- 1994-07-20 FI FI943431A patent/FI943431A0/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| AU3412593A (en) | 1993-08-03 |
| ZA93317B (en) | 1993-08-19 |
| SE469842C (en) | 1996-01-15 |
| WO1993014262A1 (en) | 1993-07-22 |
| DE69309893D1 (en) | 1997-05-22 |
| NO942718D0 (en) | 1994-07-20 |
| FI943431A (en) | 1994-07-20 |
| DE69309893T2 (en) | 1997-11-06 |
| SE9200152D0 (en) | 1992-01-21 |
| SE9200152L (en) | 1993-07-22 |
| NZ246713A (en) | 1995-04-27 |
| BR9305761A (en) | 1997-01-28 |
| ATE151826T1 (en) | 1997-05-15 |
| ES2102008T3 (en) | 1997-07-16 |
| FI943431A0 (en) | 1994-07-20 |
| EP0621915A1 (en) | 1994-11-02 |
| EP0621915B1 (en) | 1997-04-16 |
| NO942718L (en) | 1994-07-20 |
| AU653467B2 (en) | 1994-09-29 |
| JPH07503042A (en) | 1995-03-30 |
| SE469842B (en) | 1993-09-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |